I have all apple..
old iphone is left in the car or work, unlocked with a giff gaff sim, fresh itunes account with my "punting email" attached to it.
Told the mrs I sold the phone for £50 when I renewed my contract and said "here's £50 for the next round of shopping, get me loads of that Bernard Matthews frozen shit"
Edit: I know you want a single device solution, it's not a good idea doing that.